/**
 * Material You 3 (M3) Design System
 * Research Monster - SKILL.md 기준
 */

/* ============================================
   FONTS
   ============================================ */
@import url('https://fonts.googleapis.com/css2?family=Roboto+Flex:wght@400;500;600;700&display=swap');
@import url('https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap');

/* Google Sans Text는 라이선스 제한으로 대체 */
:root {
    --font-product: 'Roboto Flex', 'Inter', -apple-system, system-ui, sans-serif;
    --font-body: 'Roboto Flex', 'Inter', system-ui, sans-serif;
}

/* ============================================
   M3 COLOR SYSTEM - LIGHT MODE
   ============================================ */
:root {
    /* Surface & Background */
    --md-sys-color-background: #FFFBFE;
    --md-sys-color-surface: #FFFBFE;
    --md-sys-color-surface-variant: #E7E0EC;
    --md-sys-color-surface-container: #F3EDF7;
    --md-sys-color-surface-container-low: #F7F2FA;
    --md-sys-color-surface-container-high: #ECE6F0;
    --md-sys-color-surface-container-highest: #E6E0E9;

    /* Primary Colors */
    --md-sys-color-primary: #6750A4;
    --md-sys-color-on-primary: #FFFFFF;
    --md-sys-color-primary-container: #EADDFF;
    --md-sys-color-on-primary-container: #21005D;

    /* Secondary Colors */
    --md-sys-color-secondary: #625B71;
    --md-sys-color-on-secondary: #FFFFFF;
    --md-sys-color-secondary-container: #E8DEF8;
    --md-sys-color-on-secondary-container: #1D192B;

    /* Tertiary Colors */
    --md-sys-color-tertiary: #7D5260;
    --md-sys-color-on-tertiary: #FFFFFF;
    --md-sys-color-tertiary-container: #FFD8E4;
    --md-sys-color-on-tertiary-container: #31111D;

    /* Error Colors */
    --md-sys-color-error: #B3261E;
    --md-sys-color-on-error: #FFFFFF;
    --md-sys-color-error-container: #F9DEDC;
    --md-sys-color-on-error-container: #410E0B;

    /* Text Colors */
    --md-sys-color-on-surface: #1D1B20;
    --md-sys-color-on-surface-variant: #49454F;

    /* Outline */
    --md-sys-color-outline: #79747E;
    --md-sys-color-outline-variant: #CAC4D0;
}

/* ============================================
   M3 COLOR SYSTEM - DARK MODE
   ============================================ */
@media (prefers-color-scheme: dark) {
    :root {
        --md-sys-color-background: #1D1B20;
        --md-sys-color-surface: #1D1B20;
        --md-sys-color-surface-variant: #49454F;
        --md-sys-color-surface-container: #211F26;
        --md-sys-color-surface-container-low: #1D1B20;
        --md-sys-color-surface-container-high: #2B2930;
        --md-sys-color-surface-container-highest: #36343B;

        --md-sys-color-primary: #D0BCFF;
        --md-sys-color-on-primary: #381E72;
        --md-sys-color-primary-container: #4F378B;
        --md-sys-color-on-primary-container: #EADDFF;

        --md-sys-color-secondary: #CCC2DC;
        --md-sys-color-on-secondary: #332D41;
        --md-sys-color-secondary-container: #4A4458;
        --md-sys-color-on-secondary-container: #E8DEF8;

        --md-sys-color-tertiary: #EFB8C8;
        --md-sys-color-on-tertiary: #492532;
        --md-sys-color-tertiary-container: #633B48;
        --md-sys-color-on-tertiary-container: #FFD8E4;

        --md-sys-color-error: #F2B8B5;
        --md-sys-color-on-error: #601410;
        --md-sys-color-error-container: #8C1D18;
        --md-sys-color-on-error-container: #F9DEDC;

        --md-sys-color-on-surface: #E6E0E9;
        --md-sys-color-on-surface-variant: #CAC4D0;

        --md-sys-color-outline: #938F99;
        --md-sys-color-outline-variant: #49454F;
    }
}

/* ============================================
   MOTION SYSTEM
   ============================================ */
:root {
    /* M3 Easing Functions */
    --md-sys-motion-easing-emphasized: cubic-bezier(0.2, 0, 0, 1);
    --md-sys-motion-easing-emphasized-accelerate: cubic-bezier(0.3, 0, 0.8, 0.15);
    --md-sys-motion-easing-emphasized-decelerate: cubic-bezier(0.05, 0.7, 0.1, 1);
    --md-sys-motion-easing-standard: cubic-bezier(0.2, 0, 0, 1);
    --md-sys-motion-easing-legacy: cubic-bezier(0.4, 0, 0.2, 1);

    /* Duration Tokens */
    --md-sys-motion-duration-short1: 50ms;
    --md-sys-motion-duration-short2: 100ms;
    --md-sys-motion-duration-short3: 150ms;
    --md-sys-motion-duration-short4: 200ms;
    --md-sys-motion-duration-medium1: 250ms;
    --md-sys-motion-duration-medium2: 300ms;
    --md-sys-motion-duration-medium3: 350ms;
    --md-sys-motion-duration-medium4: 400ms;
    --md-sys-motion-duration-long1: 450ms;
    --md-sys-motion-duration-long2: 500ms;
}

/* ============================================
   SPACING SYSTEM
   ============================================ */
:root {
    --space-1: 4px;
    --space-2: 8px;
    --space-3: 12px;
    --space-4: 16px;
    --space-5: 20px;
    --space-6: 24px;
    --space-7: 28px;
    --space-8: 32px;
    --space-9: 36px;
    --space-10: 40px;
    --space-12: 48px;
    --space-16: 64px;
    --space-20: 80px;
}

/* ============================================
   TYPOGRAPHY
   ============================================ */
body {
    font-family: var(--font-body);
    font-variation-settings: 'wght' 450, 'wdth' 100;
    line-height: 1.65;
    letter-spacing: -0.01em;
    background-color: var(--md-sys-color-background);
    color: var(--md-sys-color-on-surface);
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-product);
    font-variation-settings: 'wght' 600;
    letter-spacing: -0.02em;
    line-height: 1.2;
    color: var(--md-sys-color-on-surface);
}

/* ============================================
   ELEVATION LEVELS (Surface Tints)
   ============================================ */
.surface-level-0 {
    background-color: var(--md-sys-color-surface);
    box-shadow: none;
}

.surface-level-1 {
    background-color: var(--md-sys-color-surface-container-low);
    box-shadow:
        0 1px 2px rgba(0, 0, 0, 0.05),
        0 1px 3px rgba(0, 0, 0, 0.1);
}

.surface-level-2 {
    background-color: var(--md-sys-color-surface-container);
    box-shadow:
        0 2px 4px rgba(0, 0, 0, 0.08),
        0 4px 6px rgba(0, 0, 0, 0.1);
}

.surface-level-3 {
    background-color: var(--md-sys-color-surface-container-high);
    box-shadow:
        0 4px 8px rgba(0, 0, 0, 0.12),
        0 8px 16px rgba(0, 0, 0, 0.16);
}

.surface-level-4 {
    background-color: var(--md-sys-color-surface-container-highest);
    box-shadow:
        0 8px 16px rgba(0, 0, 0, 0.16),
        0 16px 32px rgba(0, 0, 0, 0.24);
}

/* ============================================
   UTILITY CLASSES
   ============================================ */
.m3-card {
    border-radius: 24px;
    padding: var(--space-6);
    background-color: var(--md-sys-color-surface-container);
    color: var(--md-sys-color-on-surface);
}

.m3-button-filled {
    background-color: var(--md-sys-color-primary);
    color: var(--md-sys-color-on-primary);
    border: none;
    border-radius: 999px;
    padding: var(--space-3) var(--space-6);
    font-weight: 500;
    cursor: pointer;
    transition:
        background-color var(--md-sys-motion-duration-short4) var(--md-sys-motion-easing-standard),
        transform var(--md-sys-motion-duration-short2) var(--md-sys-motion-easing-emphasized);
}

.m3-button-filled:hover {
    background-color: color-mix(in srgb, var(--md-sys-color-primary) 90%, black);
}

.m3-button-outlined {
    background-color: transparent;
    color: var(--md-sys-color-primary);
    border: 1px solid var(--md-sys-color-outline);
    border-radius: 999px;
    padding: var(--space-3) var(--space-6);
    font-weight: 500;
    cursor: pointer;
}

.m3-button-text {
    background-color: transparent;
    color: var(--md-sys-color-primary);
    border: none;
    border-radius: 999px;
    padding: var(--space-2) var(--space-4);
    font-weight: 500;
    cursor: pointer;
}

/* ============================================
   RESPONSIVE LAYOUT
   ============================================ */
.layout-grid {
    display: grid;
    gap: var(--space-6);
    padding: var(--space-6);
    grid-template-columns: repeat(4, 1fr);
}

@media (min-width: 600px) {
    .layout-grid {
        grid-template-columns: repeat(8, 1fr);
        padding: var(--space-8);
    }
}

@media (min-width: 1240px) {
    .layout-grid {
        grid-template-columns: repeat(12, 1fr);
        padding: var(--space-10);
        max-width: 1440px;
        margin: 0 auto;
    }
}