/* ================== リセット＆基本設定 ================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

:root {
    /* ライトモード */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #efefef;
    --text-primary: #1a1a1a;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --border-color: #e0e0e0;
    --accent-color: #5b6ef5;
    --accent-hover: #4654d4;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
    --card-shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.12);
}

@media (prefers-color-scheme: dark) {
    :root {
        /* ダークモード */
        --bg-primary: #1a1a1a;
        --bg-secondary: #2d2d2d;
        --bg-tertiary: #3a3a3a;
        --text-primary: #f5f5f5;
        --text-secondary: #b0b0b0;
        --text-tertiary: #808080;
        --border-color: #404040;
        --accent-color: #6b7aff;
        --accent-hover: #5b6aef;
        --success-color: #34d399;
        --warning-color: #fbbf24;
        --error-color: #f87171;
        --card-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
        --card-shadow-hover: 0 4px 12px rgba(0, 0, 0, 0.5);
    }
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Hiragino Sans', 'Noto Sans JP', sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

/* ================== レイアウト ================== */
#app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* ================== ナビゲーション ================== */
.navbar {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--card-shadow);
    gap: 1rem;
}

.navbar-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-color);
}

.navbar-actions {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.theme-toggle {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 0.5rem;
    transition: background-color 0.2s;
}

.theme-toggle:hover {
    background-color: var(--bg-tertiary);
}

.logout-btn {
    padding: 0.5rem 1rem;
    background-color: var(--error-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    transition: background-color 0.2s;
}

.logout-btn:hover {
    background-color: #dc2626;
}

.user-info {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* ================== タブナビゲーション ================== */
.tab-navigation {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-secondary);
    gap: 0;
}

.tab-button {
    flex: 1;
    padding: 1rem;
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    transition: all 0.2s;
}

.tab-button.active {
    color: var(--accent-color);
    border-bottom-color: var(--accent-color);
}

.tab-button:hover {
    color: var(--text-primary);
}

/* ================== ページコンテンツ ================== */
.page-content {
    flex: 1;
    padding: 1.5rem;
    max-width: 100%;
    margin: 0 auto;
    width: 100%;
}

@media (min-width: 768px) {
    .page-content {
        max-width: 900px;
    }
}

/* ================== 認証ページ ================== */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    background: linear-gradient(135deg, var(--accent-color), #667eea);
}

.auth-box {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    width: 100%;
    max-width: 400px;
}

.auth-box h2 {
    margin-bottom: 1.5rem;
    text-align: center;
    color: var(--text-primary);
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.form-group input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(91, 110, 245, 0.1);
}

.btn-primary {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
}

.btn-primary:disabled {
    background-color: var(--text-tertiary);
    cursor: not-allowed;
}

.auth-toggle {
    text-align: center;
    margin-top: 1.5rem;
    font-size: 0.9rem;
}

.auth-toggle button {
    background: none;
    border: none;
    color: var(--accent-color);
    cursor: pointer;
    text-decoration: underline;
    font-weight: 600;
}

.oauth-buttons {
    margin-top: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.oauth-btn {
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.oauth-btn:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--accent-color);
}

.error-message {
    background-color: var(--error-color);
    color: white;
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
}

.success-message {
    background-color: var(--success-color);
    color: white;
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
}

/* ================== ホーム画面 ================== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    text-align: center;
    box-shadow: var(--card-shadow);
    transition: transform 0.2s, box-shadow 0.2s;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--card-shadow-hover);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.progress-section {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    margin-bottom: 2rem;
    box-shadow: var(--card-shadow);
}

.progress-label {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background-color: var(--bg-tertiary);
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), #667eea);
    width: 0%;
    transition: width 0.3s ease;
}

.study-goal-section {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    box-shadow: var(--card-shadow);
}

.study-goal-section h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.goal-input-group {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.goal-input-group input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    font-size: 1rem;
}

.goal-input-group button {
    padding: 0.75rem 1.5rem;
    background-color: var(--accent-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    transition: background-color 0.2s;
}

.goal-input-group button:hover {
    background-color: var(--accent-hover);
}

.goal-display {
    padding: 1rem;
    background-color: var(--bg-tertiary);
    border-radius: 0.5rem;
    border-left: 4px solid var(--accent-color);
}

.goal-display strong {
    color: var(--accent-color);
}

/* ================== 学習画面 ================== */
.vocabulary-card {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    margin-bottom: 1rem;
    box-shadow: var(--card-shadow);
    transition: all 0.2s;
}

.vocabulary-card:hover {
    box-shadow: var(--card-shadow-hover);
    transform: translateY(-2px);
}

.vocab-word {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent-color);
    margin-bottom: 0.5rem;
}

.vocab-reading {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.vocab-meaning {
    font-size: 1rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.vocab-example {
    background-color: var(--bg-tertiary);
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
    border-left: 3px solid var(--accent-color);
}

.vocab-example-title {
    font-weight: 600;
    font-size: 0.85rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.vocab-example-text {
    font-size: 0.95rem;
    color: var(--text-primary);
    line-height: 1.7;
}

.vocab-scenario {
    background-color: var(--bg-tertiary);
    padding: 1rem;
    border-radius: 0.5rem;
    border-left: 3px solid var(--success-color);
}

.vocab-scenario-title {
    font-weight: 600;
    font-size: 0.85rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.vocab-scenario-text {
    font-size: 0.95rem;
    color: var(--text-primary);
    line-height: 1.7;
}

.vocab-actions {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

.btn-small {
    flex: 1;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 0.4rem;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 600;
    transition: all 0.2s;
}

.btn-small:hover {
    background-color: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
}

.btn-small.marked {
    background-color: var(--success-color);
    color: white;
    border-color: var(--success-color);
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.empty-state p {
    margin-bottom: 1.5rem;
}

.btn-add-vocab {
    padding: 0.75rem 1.5rem;
    background-color: var(--success-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    transition: background-color 0.2s;
}

.btn-add-vocab:hover {
    background-color: #059669;
}

.add-vocab-form {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    margin-bottom: 2rem;
    box-shadow: var(--card-shadow);
}

.form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

@media (max-width: 600px) {
    .form-grid {
        grid-template-columns: 1fr;
    }
}

.add-vocab-form textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    font-size: 0.95rem;
    font-family: inherit;
    resize: vertical;
    min-height: 80px;
    margin-bottom: 1rem;
}

.add-vocab-form textarea:focus {
    outline: none;
    border-color: var(--accent-color);
}

.btn-submit {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--success-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    transition: background-color 0.2s;
}

.btn-submit:hover {
    background-color: #059669;
}

.btn-cancel {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--error-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    margin-top: 0.5rem;
    transition: background-color 0.2s;
}

.btn-cancel:hover {
    background-color: #dc2626;
}

/* ================== ユーザー画面 ================== */
.user-profile {
    background-color: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 0.75rem;
    margin-bottom: 2rem;
    box-shadow: var(--card-shadow);
}

.profile-field {
    margin-bottom: 1.5rem;
}

.profile-field label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.profile-field input {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    font-size: 1rem;
}

.profile-field input:focus {
    outline: none;
    border-color: var(--accent-color);
}

.btn-update-profile {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--success-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    transition: background-color 0.2s;
}

.btn-update-profile:hover {
    background-color: #059669;
}

.danger-zone {
    background-color: var(--error-color);
    background-color: rgba(239, 68, 68, 0.1);
    border: 2px solid var(--error-color);
    padding: 1.5rem;
    border-radius: 0.75rem;
    margin-top: 2rem;
}

.danger-zone h3 {
    color: var(--error-color);
    margin-bottom: 1rem;
}

.btn-delete-account {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--error-color);
    color: white;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 1rem;
    transition: background-color 0.2s;
}

.btn-delete-account:hover {
    background-color: #dc2626;
}

/* ================== ローディング＆スピナー ================== */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    color: var(--text-secondary);
}

.spinner {
    border: 4px solid var(--bg-tertiary);
    border-top: 4px solid var(--accent-color);
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 1s linear infinite;
    margin-right: 1rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ================== レスポンシブ ================== */
@media (max-width: 768px) {
    .page-content {
        padding: 1rem;
    }

    .navbar {
        flex-wrap: wrap;
    }

    .navbar-title {
        width: 100%;
        margin-bottom: 0.5rem;
    }

    .stat-card {
        padding: 1rem;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .form-grid {
        grid-template-columns: 1fr;
    }

    .tab-button {
        padding: 0.75rem;
        font-size: 0.85rem;
    }
}

@media (max-width: 480px) {
    .navbar {
        padding: 0.75rem;
    }

    .navbar-title {
        font-size: 1.1rem;
    }

    .page-content {
        padding: 0.75rem;
    }

    .auth-box {
        padding: 1.5rem;
    }

    .vocabulary-card {
        padding: 1rem;
    }

    .vocab-word {
        font-size: 1.25rem;
    }

    .vocab-actions {
        flex-direction: column;
    }

    .btn-small {
        width: 100%;
    }
}

/* ================== ユーティリティ ================== */
.hidden {
    display: none;
}

.text-center {
    text-align: center;
}

.mt-2 {
    margin-top: 1rem;
}

.mb-2 {
    margin-bottom: 1rem;
}

.gap-1 {
    gap: 0.5rem;
}