:root {
    --gap: 24px;
    --content-gap: 20px;
    --radius: 8px;
    --theme: #1d1e20;
    --entry: #2e2e33;
    --primary: #ddd;
    --secondary: #999;
    --tertiary: #666;
    --content: #fff;
    --border: #333;
    --accent: #bb86fc;
    --success: #52b788;
    --pause: #f77f00;
}

@media (prefers-color-scheme: light) {
    :root {
        --theme: #fff;
        --entry: #f5f5f5;
        --primary: #333;
        --secondary: #666;
        --tertiary: #999;
        --content: #000;
        --border: #e6e6e6;
        --accent: #5d4e8c;
        --success: #2a9d8f;
        --pause: #e76f51;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background: var(--theme);
    color: var(--primary);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: var(--gap);
    font-size: 18px;
    line-height: 1.6;
}

.container {
    background: var(--theme);
    max-width: 400px;
    width: 100%;
}

h1 {
    text-align: center;
    color: var(--content);
    margin-bottom: 40px;
    font-size: 32px;
    font-weight: 700;
}

.setup-section {
    margin-bottom: 40px;
}

.input-group {
    margin-bottom: 24px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    color: var(--secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

input[type="text"],
input[type="number"] {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 16px;
    background: var(--entry);
    color: var(--primary);
    transition: border-color 0.2s;
}

input[type="text"]:focus,
input[type="number"]:focus {
    outline: none;
    border-color: var(--accent);
}

input:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.timer-display {
    text-align: center;
    margin: 60px 0;
}

.current-topic {
    font-size: 16px;
    color: var(--secondary);
    margin-bottom: 16px;
    min-height: 24px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.timer {
    font-size: 72px;
    font-weight: 200;
    color: var(--content);
    font-variant-numeric: tabular-nums;
    line-height: 1;
    letter-spacing: -2px;
}

.status {
    font-size: 14px;
    color: var(--tertiary);
    margin-top: 16px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.controls {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-bottom: 60px;
}

.btn {
    padding: 10px 24px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 400;
    cursor: pointer;
    transition: all 0.2s;
    text-transform: uppercase;
    letter-spacing: 1px;
    background: transparent;
    color: var(--primary);
}

.btn:hover:not(:disabled) {
    background: var(--entry);
}

.btn:active:not(:disabled) {
    opacity: 0.8;
}

.btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

.btn-start {
    border-color: var(--success);
    color: var(--success);
}

.btn-start:hover:not(:disabled) {
    background: var(--success);
    color: var(--theme);
}

.btn-pause {
    border-color: var(--pause);
    color: var(--pause);
}

.btn-pause:hover:not(:disabled) {
    background: var(--pause);
    color: var(--theme);
}

.btn-reset {
    border-color: var(--tertiary);
    color: var(--tertiary);
}

.btn-reset:hover:not(:disabled) {
    border-color: var(--secondary);
    color: var(--secondary);
}

.stats {
    margin-top: 60px;
    padding-top: 40px;
    border-top: 1px solid var(--border);
}

.stats h3 {
    color: var(--content);
    margin-bottom: 24px;
    font-size: 20px;
    font-weight: 600;
}

.history {
    max-height: 240px;
    overflow-y: auto;
}

.no-sessions {
    text-align: center;
    color: var(--tertiary);
    padding: 20px;
    font-size: 14px;
}

.session-item {
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
    transition: opacity 0.2s;
}

.session-item:last-child {
    border-bottom: none;
}

.session-item:hover {
    opacity: 0.8;
}

.session-topic {
    font-size: 16px;
    color: var(--primary);
    margin-bottom: 4px;
}

.session-meta {
    font-size: 14px;
    color: var(--tertiary);
}

@media (max-width: 600px) {
    .timer {
        font-size: 56px;
    }
    
    .controls {
        gap: 8px;
    }
    
    .btn {
        padding: 8px 16px;
        font-size: 12px;
    }
}