:root {
    --primary: #ff6b6b;
    --secondary: #4ecdc4;
    --bg: #f7f9fc;
    --card-bg: #ffffff;
    --text: #2d3436;
    --input-border: #dfe6e9;
}

body.dark-mode {
    --bg: #1a1a2e;
    --card-bg: #16213e;
    --text: #e9ecef;
    --input-border: #0f3460;
}

body {
    font-family: 'Segoe UI', sans-serif;
    background-color: var(--bg);
    color: var(--text);
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    transition: 0.3s;
}

.container {
    background: var(--card-bg);
    padding: 2.5rem;
    border-radius: 24px;
    box-shadow: 0 15px 35px rgba(0,0,0,0.15);
    text-align: center;
    width: 350px;
    position: relative;
}

.theme-toggle {
    position: absolute;
    top: 20px;
    right: 20px;
    cursor: pointer;
    background: none;
    border: 1px solid var(--input-border);
    padding: 5px 10px;
    border-radius: 20px;
    color: var(--text);
}

.timer-display {
    font-size: 5.5rem;
    font-weight: 800;
    margin: 1rem 0;
}

.mode-buttons {
    margin-bottom: 20px;
    display: flex;
    justify-content: center;
    gap: 5px;
}

.mode-buttons button {
    background: #eee;
    border: none;
    padding: 5px 10px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 0.8rem;
}

.controls button {
    padding: 12px 20px;
    font-weight: bold;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    margin: 0 5px;
}

#start { background: var(--secondary); color: white; }
#pause { background: #ffe66d; color: #333; }
#reset { background: var(--primary); color: white; }

.settings {
    margin-top: 1.5rem;
    padding-top: 1rem;
    border-top: 2px solid var(--input-border);
}

input[type="number"] {
    width: 60px;
    padding: 8px;
    border-radius: 8px;
    border: 1px solid var(--input-border);
    background: var(--card-bg);
    color: var(--text);
}

.set-btn {
    background: #6c757d;
    color: white;
    border: none;
    padding: 8px 12px;
    border-radius: 8px;
    cursor: pointer;
}

button:disabled { opacity: 0.4; }