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Dark Overlay Architecture

Dark overlays create depth and separation in the UI through shadows, modal backdrops, dimming effects, and depth indicators.
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|  DARK OVERLAY VISUAL HIERARCHY                                                  |
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|                                                                                 |
|   ELEVATION SYSTEM                                                             |
|   ================                                                             |
|                                                                                 |
|                     +----------------------------------------------+           |
|   Level 4 (30%)    |              MODAL DIALOG                    |           |
|   Topmost          |         +----------------------+              |           |
|                     |         |    Dialog Content    |              |           |
|                     |         +----------------------+              |           |
|                     +----------------------------------------------+           |
|                          ^                                                     |
|                          | overlay-dark-4 (30% black)                          |
|                          |                                                     |
|                     +----+---------------------------------------------+       |
|   Level 3 (20%)    |                DROPDOWN MENU                      |       |
|   High elevation   |   +--------------------+                          |       |
|                     |   |  Option 1         |                          |       |
|                     |   |  Option 2         |                          |       |
|                     |   +--------------------+                          |       |
|                     +--------------------------------------------------+       |
|                          ^                                                     |
|                          | overlay-dark-3 (20% black)                          |
|                          |                                                     |
|                     +----+---------------------------------------------+       |
|   Level 2 (10%)    |                  SIDEBAR                          |       |
|   Medium elevation |   File Explorer                                   |       |
|                     |   Project Files                                   |       |
|                     +--------------------------------------------------+       |
|                          ^                                                     |
|                          | overlay-dark-2 (10% black)                          |
|                          |                                                     |
|                     +----+---------------------------------------------+       |
|   Level 1 (5%)     |                   CONTENT                         |       |
|   Base elevation   |   Main editor/terminal area                       |       |
|                     +--------------------------------------------------+       |
|                                                                                 |
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Why Black for Dark Overlays?

Unlike light overlays which derive from theme text color, dark overlays use a fixed black value.
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|  WHY BLACK FOR DARK OVERLAYS                                                    |
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|                                                                                 |
|   LIGHT OVERLAYS                          DARK OVERLAYS                        |
|   ==============                          =============                        |
|                                                                                 |
|   Source: Theme text color                Source: Black (fixed)                |
|   Adapts to theme                         Universal behavior                   |
|                                                                                 |
|   REASONS FOR FIXED BLACK:                                                     |
|   ========================                                                      |
|                                                                                 |
|   1. UNIVERSAL DARKENING                                                       |
|      Black works to darken any background                                     |
|                                                                                 |
|   2. NO HUE SHIFT                                                              |
|      Pure black does not introduce unwanted color                             |
|                                                                                 |
|   3. PREDICTABLE BEHAVIOR                                                      |
|      Same shadow appearance across themes                                      |
|                                                                                 |
|   4. PERFORMANCE                                                               |
|      No variable resolution needed                                             |
|                                                                                 |
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Dialog Shadow System

Dialogs need prominent shadows to establish elevation.
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|  DIALOG SHADOW LAYER ANALYSIS                                                   |
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|                                                                                 |
|   LARGE DIALOG SHADOW                                                          |
|   ===================                                                           |
|                                                                                 |
|   offset-x: 0          No horizontal offset (centered shadow)                  |
|   offset-y: 12px       12px below element (downward light source)              |
|   blur-radius: 48px    Large blur for soft ambient shadow                      |
|   opacity: 40%         Heavy but not solid                                     |
|                                                                                 |
|   +---------------------------------------------------------------------+      |
|   |                                                                     |      |
|   |            +-----------------------------------+                   |      |
|   |            |                                   |                   |      |
|   |            |        DIALOG CONTENT             |                   |      |
|   |            |                                   |                   |      |
|   |            +-----------------------------------+                   |      |
|   |              ....................................                   |      |
|   |               ..................................                    |      |
|   |                 ..............................                      |      |
|   |                   ..........................                        |      |
|   |                      ....................                           |      |
|   |                           ..........                                |      |
|   |                                                                     |      |
|   |   . = Shadow blur area (48px radius, 40% opacity)                  |      |
|   |                                                                     |      |
|   +---------------------------------------------------------------------+      |
|                                                                                 |
+---------------------------------------------------------------------------------+
|                                                                                 |
|   SMALL POPOVER SHADOW                                                         |
|   ====================                                                          |
|                                                                                 |
|   offset-y: 4px        Small offset (subtle elevation)                         |
|   blur-radius: 12px    Tight blur (crisp edges)                                |
|   opacity: 15%         Subtle appearance                                       |
|                                                                                 |
|   Use case: Tooltips, dropdowns, small popovers                               |
|                                                                                 |
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Modal backdrops use 70% black opacity - an industry standard.
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|  MODAL BACKDROP PSYCHOLOGY                                                      |
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|                                                                                 |
|   70% BLACK OPACITY                                                            |
|   =================                                                             |
|                                                                                 |
|   PURPOSE:                                                                     |
|   ========                                                                     |
|                                                                                 |
|   1. FOCUS ATTENTION                                                           |
|      Darkening the background directs user focus to the modal                 |
|      70% is dark enough to clearly separate layers                            |
|                                                                                 |
|   2. INDICATE MODAL STATE                                                      |
|      Users understand they must interact with the dialog                      |
|      Background becomes "unreachable"                                         |
|                                                                                 |
|   3. REDUCE VISUAL NOISE                                                       |
|      Complex UI behind modal becomes muted                                    |
|      Dialog content stands out                                                |
|                                                                                 |
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|                                                                                 |
|   WHY 70%?                                                                     |
|   ========                                                                     |
|                                                                                 |
|   +---------------------------------------------------------------------+      |
|   |  50%: Too light - background still distracting                     |      |
|   |  60%: Borderline - works but not strong                            |      |
|   |  70%: OPTIMAL - clear separation without total blackout    <---    |      |
|   |  80%: Acceptable - almost too dark                                 |      |
|   |  90%: Too dark - feels oppressive, hard to see context             |      |
|   +---------------------------------------------------------------------+      |
|                                                                                 |
|   70% black is the industry standard for modal backdrops                      |
|                                                                                 |
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Backdrop vs Dark Overlay

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|  BACKDROP VS DARK OVERLAY COMPARISON                                            |
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|                                                                                 |
|   MODAL BACKDROP                          DARK OVERLAY-4                       |
|   ==============                          ===============                       |
|                                                                                 |
|   70% opacity                             30% opacity                          |
|                                                                                 |
|   Used for:                               Used for:                            |
|   * Full-screen modal backdrops           * Heavy shadows                      |
|   * Blocking overlays                     * Strong dimming effects             |
|   * Focus lock indicators                 * Card elevation shadows             |
|                                                                                 |
|   +---------------------------------------------------------------------+      |
|   |                                                                     |      |
|   |   70% backdrop        30% overlay-dark-4   10% overlay-dark-2      |      |
|   |   ################    ######..........    ....##..........        |      |
|   |                                                                     |      |
|   |   Modal backdrop      Card shadow          Subtle shadow           |      |
|   |   (blocks content)    (elevation cue)      (light depth)           |      |
|   |                                                                     |      |
|   +---------------------------------------------------------------------+      |
|                                                                                 |
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Focus and Hover State Hierarchy

Interactive states progress through increasing overlay opacity.
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|  FOCUS AND HOVER STATE HIERARCHY                                                |
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|                                                                                 |
|   STATE PROGRESSION:                                                           |
|   ==================                                                           |
|                                                                                 |
|   Normal --> Hover --> Focus --> Active --> Selected                          |
|     0%        8%       12%       16%         20%                               |
|                                                                                 |
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|                                                                                 |
|   NORMAL STATE                                                                 |
|   Background: transparent (0%)                                                 |
|   ................................................................             |
|                                                                                 |
|   HOVER STATE                                                                  |
|   Background: overlay-light-1 (8%)                                             |
|   #...............................................................             |
|                                                                                 |
|   FOCUS STATE                                                                  |
|   Background: overlay-light-2 (12%)                                            |
|   + Border ring for accessibility                                              |
|   ##..............................................................             |
|                                                                                 |
|   ACTIVE/PRESSED STATE                                                         |
|   Background: overlay-light-3 (16%)                                            |
|   ###.............................................................             |
|                                                                                 |
|   SELECTED STATE                                                               |
|   Background: 20% of primary color (not neutral)                               |
|   Uses primary color instead of neutral overlay                                |
|   ####............................................................             |
|                                                                                 |
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Transparent Border System

Borders can use transparency for adaptive appearance.
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|  TRANSPARENT BORDER SYSTEM                                                      |
+---------------------------------------------------------------------------------+
|                                                                                 |
|   DARK BORDER: 20% black + transparent                                         |
|   ========================================                                      |
|                                                                                 |
|   Result: 20% black semi-transparent border                                    |
|   Adapts to ANY background - darkens by 20%                                   |
|                                                                                 |
|   +--------------------------------------------------------------------+       |
|   |  On light background:   ................ (visible as light gray)  |       |
|   |  On dark background:    ################ (visible as dark line)   |       |
|   |  Always visible, always appropriate                               |       |
|   +--------------------------------------------------------------------+       |
|                                                                                 |
|   ADAPTIVE DIVIDERS                                                            |
|   =================                                                             |
|                                                                                 |
|   Theme text color at 15% - adapts automatically                              |
|                                                                                 |
|   Dark theme: 15% of light gray on dark background                            |
|   Light theme: 15% of near-black on light background                          |
|                                                                                 |
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Light Theme Shadow Adjustments

Light themes need less shadow intensity because dark-on-light is more visible.
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|  DARK VS LIGHT THEME SHADOW COMPARISON                                          |
+---------------------------------------------------------------------------------+
|                                                                                 |
|   DARK THEME                              LIGHT THEME                          |
|   ==========                              ===========                          |
|                                                                                 |
|   overlay-light-1: 8%                     overlay-light-1: 3%                  |
|   overlay-light-2: 12%                    overlay-light-2: 5%                  |
|   overlay-light-3: 16%                    overlay-light-3: 8%                  |
|   overlay-light-4: 20%                    overlay-light-4: 12%                 |
|                                                                                 |
|   KEY INSIGHT:                                                                 |
|   ============                                                                 |
|                                                                                 |
|   In light theme, "light overlays" actually use BLACK with lower opacity      |
|   The semantic meaning is "interaction highlight" not "add white"             |
|                                                                                 |
|   Light themes need LESS intensity to achieve the same visual effect          |
|   because dark-on-light is naturally more visible than light-on-dark          |
|                                                                                 |
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Shadow and Overlay Design Principles

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|  SHADOW AND OVERLAY DESIGN PRINCIPLES                                           |
+---------------------------------------------------------------------------------+
|                                                                                 |
|   1. ELEVATION CORRELATES WITH SHADOW INTENSITY                                |
|      Higher elements cast stronger shadows                                     |
|      Level 1: 5% -> Level 2: 10% -> Level 3: 20% -> Level 4: 30%             |
|                                                                                 |
|   2. MODAL BACKDROPS USE FIXED 70% OPACITY                                     |
|      Industry standard for focus attention                                     |
|      Strong enough to separate, not so dark as to feel oppressive             |
|                                                                                 |
|   3. DARK OVERLAYS USE BLACK (UNIVERSAL)                                       |
|      Unlike light overlays which adapt to theme text color                    |
|      Black works universally for darkening                                     |
|                                                                                 |
|   4. CONTEXT MENUS USE SOLID BACKGROUNDS                                       |
|      Not transparent - ensures readability                                     |
|      Elevation communicated through shadow, not transparency                  |
|                                                                                 |
|   5. THEME-SPECIFIC SHADOW INTENSITY                                           |
|      Light themes need LESS shadow intensity                                  |
|      Dark-on-light is more visible than light-on-dark                         |
|                                                                                 |
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Summary: Shadow Pattern Reference

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|  SHADOW PATTERN REFERENCE                                                       |
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|                                                                                 |
|   PATTERN            TRANSPARENT     OPACITY     USE CASE                      |
|   -------            -----------     -------     --------                      |
|                                                                                 |
|   overlay-dark-1     95%             5%          Subtle shadows                |
|   overlay-dark-2     90%             10%         Light shadows                 |
|   overlay-dark-3     80%             20%         Medium shadows                |
|   overlay-dark-4     70%             30%         Heavy shadows                 |
|   overlay-backdrop   30%             70%         Modal backdrop                |
|                                                                                 |
|   SHADOW             OFFSET    BLUR      OPACITY     USE CASE                  |
|   ------             ------    ----      -------     --------                  |
|                                                                                 |
|   dialog-shadow      12px      48px      40%         Dialog elevation          |
|   dialog-shadow-sm   4px       12px      15%         Small popover             |
|                                                                                 |
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State Transitions

Learn about hover, active, and disabled state derivations